That temp is defniitely low - and yes, a faulty 'stat will affect economy.

Sadly, there's nothing wrong with either of my stats and despite doing virtually nothing except 40 mile motorway runs with cruise control set at 70, I can't get mine to return any more than 35mpg. While I'm sat on the motorway the swingometer will show 45-50mpg, but the second I hit town, traffic lights and traffic, the economy just plummets.

I do 100% town driving and avg around 32-33 if i'm lucky. I managed to get close to 35mpg with a mix of motorway and town. I don't think the remap improved the economy or worsend it. DPF delete is on the cards should see a 5mpg improvement.

Danny, yours is a manual right? If so I'd expect it to be better but by 10mpg+ thats a pretty big difference!

I do 100% town driving and avg around 32-33 if i'm lucky. I managed to get close to 35mpg with a mix of motorway and town. I don't think the remap improved the economy or worsend it. DPF delete is on the cards should see a 5mpg improvement.

Danny, yours is a manual right? If so I'd expect it to be better but by 10mpg+ thats a pretty big difference!

So theres a main thermostat and an EGR one too.. I'm guessing that checking the engine temps won't really tell you which item is duff?

We are not supposed to be needing the ECT, or the other hidden data.

No, the temperature won't tell which is at fault, but will gives some pretty good clues. Very low ECT averages are typically the EGR thermostat, can be open from room temperature, so usually a long warm up time/mileage as well.

But often, even after the EGR 'stat change, the temperature is still lower than it ought to be. the main 'stats seem to lose their optimum range and run low, slowly degrading over time, rather than a complete failure.

I notice you ask does it affect performance. I've got a similar temperature problem and have run some performance figures with my Racelogic V-box (GPS device).

I've only had my 335d a week (it's done 80,000m) and noticed the temperature runs in the high 70s, regardless of type of driving, taking a very long time to get there.

Some of the figures I got were:
0-60 = 6.1s
0-100 = 14.5s

which is down on figures I've read for a standard car, from magazine articles and the likes of Carlos.

Fuel consumption over last week, which was all short journeys around town has been 26mpg. I hope to change the EGR stat next week and see if it makes any difference.

Regarding te DPF delete, there was talk of it being a requirement of the MOT from 2012 to have one in place if the car was build with one, anyone got any further info on this? I do like the idea of deleting it, it must restrict the engine but I don't want to be blowing out a cloud of black smoke.

I know it's been some time but did you replace the EGRs and did it improve your mpg?

I did replace the EGR stat, and found the old one to be sticking open. It made a little difference to the temperature but replacing the main stat is what put things right. Straight away it would (once up to temperature) sit at 89 on the motorway and over 90 around town.

Hi, got a 330d, e92 and with an outside temperature of -2 degrees it took 3 miles of urban driving and 25 mins of motorway driving (70mph ish) to get to 82 degrees? Is this normal or should I take it to the dealers for replacement thermostats.
Thanks

I have a 08 330d auto, i have had it two weeks just over, and i think its bad of fuel. but its getting better, i think its my driving style as i have never owned an auto. I measured it tank to tank it managed 31mpg and on the i drive did 30mpg, probably 50/50 town and dual carriageway driving.

I have got low coolant temp also, 79c is about all it manages no matter how fast or slow i drive, so its booked in for AUC to sort my low coolant temp. Also noticed mine after a 20-30 mile drive pulling up to a stop it misfires slightly and the rev counter bounces about abit. Hopefully everything is linked and bmw find a fault which helps my mpg